
/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>


static ngx_inline void *ngx_palloc_small(ngx_pool_t *pool, size_t size,ngx_uint_t align);
static void *ngx_palloc_block(ngx_pool_t *pool, size_t size);
static void *ngx_palloc_large(ngx_pool_t *pool, size_t size);


/*
 *@brief:创建内存池接口
 *@para:size_t size: 内存池大小;
 *	 	ngx_log_t *log: 日志上下文;
 *
 *@return value:
 */
ngx_pool_t * ngx_create_pool(size_t size, ngx_log_t *log)
{
    ngx_pool_t  *p;

    p = ngx_memalign(NGX_POOL_ALIGNMENT, size, log);
    if (p == NULL) {
        return NULL;
    }

    p->d.last = (u_char *) p + sizeof(ngx_pool_t); //
    p->d.end = (u_char *) p + size; //
    p->d.next = NULL;
    p->d.failed = 0;

    size = size - sizeof(ngx_pool_t);  //实际可用空间的大小;
    p->max = (size < NGX_MAX_ALLOC_FROM_POOL) ? size : NGX_MAX_ALLOC_FROM_POOL;

    p->current = p; //指向当前申请的内存块地址;
    p->chain = NULL;
    p->large = NULL;
    p->cleanup = NULL;
    p->log = log;

    return p;
}

/*
 *@brief:销毁内存池接口
 *@para: ngx_pool_t *pool:内存池的上下文
 *
 *@return value:
 */
void ngx_destroy_pool(ngx_pool_t *pool)
{
    ngx_pool_t          *p, *n;
    ngx_pool_large_t    *l;
    ngx_pool_cleanup_t  *c;
	/*
	 *@循环遍历内存块，执行对应的清理回调函数;
	 *
	 */
    for (c = pool->cleanup; c; c = c->next) {
        if (c->handler) {
            ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, pool->log, 0, "run cleanup: %p", c);
            c->handler(c->data);
        }
    }

#if (NGX_DEBUG)

    /*
     * we could allocate the pool->log from this pool
     * so we cannot use this log while free()ing the pool
     */

    for (l = pool->large; l; l = l->next) {
        ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, pool->log, 0, "free: %p", l->alloc);
    }

    for (p = pool, n = pool->d.next; /* void */; p = n, n = n->d.next) {
        ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, pool->log, 0,"free: %p, unused: %uz", p, p->d.end - p->d.last);
        if (n == NULL) {
            break;
        }
    }

#endif

    for (l = pool->large; l; l = l->next) {
        if (l->alloc) {
            ngx_free(l->alloc);  //执行大内存块的清理函数;
        }
    }

    for (p = pool, n = pool->d.next; /* void */; p = n, n = n->d.next) {
        ngx_free(p);

        if (n == NULL) {
            break;
        }
    }
}

/*
 *@brief:重置内存池
 *@para:ngx_pool_t *pool:内存池的上下文 
 *
 *@return value:void 
 */
void ngx_reset_pool(ngx_pool_t *pool)
{
    ngx_pool_t        *p;
    ngx_pool_large_t  *l;
	/*
	 *@description:释放掉所有的大内存块;
	 */
    for (l = pool->large; l; l = l->next) {
        if (l->alloc) {
            ngx_free(l->alloc);
        }
    }
	/*
	 *@description:小内存块全部置位;
	 */
    for (p = pool; p; p = p->d.next) {
        p->d.last = (u_char *) p + sizeof(ngx_pool_t);
        p->d.failed = 0; //计数器置0;
    }

    pool->current = pool;
    pool->chain = NULL;
    pool->large = NULL;
}

/*
 *@brief:提供给外部的申请内存接口;
 *@para: ngx_pool_t *pool:
 *		 size_t  size:
 *@return value:
 */
void * ngx_palloc(ngx_pool_t *pool, size_t size)
{
#if !(NGX_DEBUG_PALLOC)
    if (size <= pool->max) {  
        return ngx_palloc_small(pool, size, 1);
    }
#endif

    return ngx_palloc_large(pool, size);
}

/*
 *@brief:申请内存块的接口
 *@para: ngx_pool_t *pool: 内存池上下文;
 *		 size_t  size:想要申请的内存块大小;
 *@return value: 
 */
void * ngx_pnalloc(ngx_pool_t *pool, size_t size)
{
#if !(NGX_DEBUG_PALLOC)
    if (size <= pool->max) {
        return ngx_palloc_small(pool, size, 0);
    }
#endif

    return ngx_palloc_large(pool, size);
}

/*
 *@brief: 申请小内存块的接口;
 *@para: ngx_pool_t * pool:内存池上下文;
 *		 size_t size: 申请的内存大小;
 *		 ngx_uint_t align: 地址偏移
 *@return value:
 */
static ngx_inline void * ngx_palloc_small(ngx_pool_t *pool, size_t size, ngx_uint_t align)
{
    u_char      *m;
    ngx_pool_t  *p;

    p = pool->current;

    do {
        m = p->d.last;

        if (align) {
            m = ngx_align_ptr(m, NGX_ALIGNMENT); //对内存做地址对齐
        }
		/*
		 *@小内存块;
		 */
        if ((size_t) (p->d.end - m) >= size) {
            p->d.last = m + size;
            return m;
        }

        p = p->d.next;

    } while (p);

    return ngx_palloc_block(pool, size);
}

/*
 *@brief: 如果当前的小内存块不够的时候, 就重新申请一块小的内存块 (大小为4K)
 *@para: ngx_pool_t *pool:内存池的上下文 
 *		 size_t size:要申请的内存大小;
 *
 *@return value:
 */
static void * ngx_palloc_block(ngx_pool_t *pool, size_t size)
{
    u_char      *m;
    size_t       psize;
    ngx_pool_t  *p, *new;

    psize = (size_t) (pool->d.end - (u_char *) pool);

    m = ngx_memalign(NGX_POOL_ALIGNMENT, psize, pool->log);
    if (m == NULL) {
        return NULL;
    }

    new = (ngx_pool_t *) m;

    new->d.end = m + psize;
    new->d.next = NULL;
    new->d.failed = 0;

    m += sizeof(ngx_pool_data_t);
    m = ngx_align_ptr(m, NGX_ALIGNMENT);
    new->d.last = m + size;

    for (p = pool->current; p->d.next; p = p->d.next) {
        if (p->d.failed++ > 4) {
            pool->current = p->d.next;
        }
    }

    p->d.next = new;

    return m;
}

/*
 *@brief:申请一块大的内存块
 *@para:ngx_pool_t *pool:
 *		size_t size: 
 *@return value:
 */
static void * ngx_palloc_large(ngx_pool_t *pool, size_t size)
{
    void              *p;
    ngx_uint_t         n;
    ngx_pool_large_t  *large;

    p = ngx_alloc(size, pool->log);
    if (p == NULL) {
        return NULL;
    }

    n = 0;
	/*
	 *@brief:
	 */
    for (large = pool->large; large; large = large->next) {
        if (large->alloc == NULL) {
            large->alloc = p;
            return p;
        }
		/*
		 *@description:如果大内存块链表有超过3个大内存块, 如果计数器大于3;
		 */
        if (n++ > 3) {
            break;
        }
    }

	/*
	 *@brief:
	 */
    large = ngx_palloc_small(pool, sizeof(ngx_pool_large_t), 1);
    if (large == NULL) {
        ngx_free(p);
        return NULL;
    }

    large->alloc = p;
    large->next = pool->large;
    pool->large = large;

    return p;
}

/*
 *@brief:从内存池里申请一块大内存的头, 再从系统中申请一块size的内存.
 *@para: ngx_pool_t *pool:内存池的上下文;
 *		 size_t size: 内存大小;
 *		 size_t alignment:偏移地址;
 */
void * ngx_pmemalign(ngx_pool_t *pool, size_t size, size_t alignment)
{
    void              *p;
    ngx_pool_large_t  *large;

    p = ngx_memalign(alignment, size, pool->log);
    if (p == NULL) {
        return NULL;
    }

    large = ngx_palloc_small(pool, sizeof(ngx_pool_large_t), 1);
    if (large == NULL) {
        ngx_free(p);
        return NULL;
    }

    large->alloc = p;
    large->next = pool->large;
    pool->large = large;

    return p;
}


/*
 *@brief:释放大内存块
 *@para: ngx_pool_t *pool:内存池的上下文 
 *		 void * p: 要被释放内存地址为p的内存块.
 *@return value:
 */
ngx_int_t ngx_pfree(ngx_pool_t *pool, void *p)
{
    ngx_pool_large_t  *l;

    for (l = pool->large; l; l = l->next) {
        if (p == l->alloc) {
            ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, pool->log, 0, "free: %p", l->alloc);
            ngx_free(l->alloc);
            l->alloc = NULL;

            return NGX_OK;
        }
    }

    return NGX_DECLINED;
}

/*
 *@brief:
 *@para:
 *
 *@return value:
 */
void * ngx_pcalloc(ngx_pool_t *pool, size_t size)
{
    void *p;

    p = ngx_palloc(pool, size);
    if (p) {
        ngx_memzero(p, size);
    }

    return p;
}

/*
 *@brief:
 *@para:ngx_pool_t *p:内存池的上下文 
 *		size_t size: 申请的内存大小;
 *
 *@return value:
 */
ngx_pool_cleanup_t * ngx_pool_cleanup_add(ngx_pool_t *p, size_t size)
{
    ngx_pool_cleanup_t  *c;

    c = ngx_palloc(p, sizeof(ngx_pool_cleanup_t));
    if (c == NULL) {
        return NULL;
    }

    if (size) {
        c->data = ngx_palloc(p, size);
        if (c->data == NULL) {
            return NULL;
        }

    } else {
        c->data = NULL;
    }

    c->handler = NULL;
    c->next = p->cleanup;

    p->cleanup = c;

    ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, p->log, 0, "add cleanup: %p", c);

    return c;
}

/*
 *@brief:清理特定fd的文件
 *@para: ngx_pool_t *p:内存池的上下文 
 *		 ngx_fd_t fd: 文件描述符
 *@return value:
 */
void ngx_pool_run_cleanup_file(ngx_pool_t *p, ngx_fd_t fd)
{
    ngx_pool_cleanup_t       *c;
    ngx_pool_cleanup_file_t  *cf;

    for (c = p->cleanup; c; c = c->next) {
        if (c->handler == ngx_pool_cleanup_file) {

            cf = c->data;

            if (cf->fd == fd) {
                c->handler(cf);
                c->handler = NULL;
                return;
            }
        }
    }
}

/*@brief:
 *@para:
 *
 *@return value:
 */
void ngx_pool_cleanup_file(void *data)
{
    ngx_pool_cleanup_file_t  *c = data;

    ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, c->log, 0, "file cleanup: fd:%d", c->fd);

    if (ngx_close_file(c->fd) == NGX_FILE_ERROR) {
        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno,ngx_close_file_n " \"%s\" failed", c->name);
    }
}

/*******************************************************************************************************************************************************************
 *@brief:nginx 删除文件
 *@para: void *data:  void * data:
 *
 *@return value:
 *******************************************************************************************************************************************************************/
void ngx_pool_delete_file(void *data)
{
    ngx_pool_cleanup_file_t  *c = data;

    ngx_err_t  err;

    ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, c->log, 0, "file cleanup: fd:%d %s", c->fd, c->name);

    if (ngx_delete_file(c->name) == NGX_FILE_ERROR) {
        err = ngx_errno;

        if (err != NGX_ENOENT) {
            ngx_log_error(NGX_LOG_CRIT, c->log, err, ngx_delete_file_n " \"%s\" failed", c->name);
        }
    }

    if (ngx_close_file(c->fd) == NGX_FILE_ERROR) {
        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno, ngx_close_file_n " \"%s\" failed", c->name);
    }
}


